2. Motion detection apparatus as claimed in claim 1, wherein the in motion dection signals of the motion region detection means and left/light/up/down motion direction detection signals of the motion direction detection means are ANDed so that information on horizontal/vertical signals is obtained through the motion magnitude detection means.

a motion direction judging section for performing an exclusive OR with respect to signals from the frame difference signal generating section, interframe vertical difference signal generating section and interframe horizontal difference signal generating section in order to detect whether or not motions in up, down, left and right directions exist; and

an exclusive OR gate element for performing an exclusive OR with respect to signals from the frame difference signal generating section and the interframe horizontal difference signal generating section in order to judge whether or not motion in left right directions exist; and

an exclusive OR gate element for performing an exclusive OR with respect to signals from the frame difference signal generating section and the interframe horizontal difference signal generating section in order to judge whether or not motions in up and down directions exits.

11. Motion detection apparatus, comprising:

motion region detection means for comparing absolute values of horizontal and vertical difference signal sums with respect to respective incoming signals and 1 frame-delayed signals and certain critical values with frame difference signals in order to detect a motion region,

a 1st sample accumulating element for accumulating outputs of the vertical difference signal absolute value generating section by k samples as its outputs;

a 2nd sample accumulating element for accumulating outputs of the horizontal difference signal absolute value generating section by k samples as its output;

a 3rd sample accumulating element for accumulating outputs of the frame difference signal generating section by k samples as its output; and

a dividing element for dividing outputs of the 2nd sample accumulating element by outputs of the 3rd sample accumulating in order to detect horizontal motion magnitudes; and

a dividing element for dividing outputs of the 1st sample accumulating element by outputs of the 3rd sample accumulating element in 227 order to detect vertical motion magnitudes.

16. Motion detection method comprising:

a motion region detection step which compares absolute values respective input signals and horizontal and vertical difference signal sums with respect to 1 frame-delayed signals and certain critical values with frame difference signals in order to detect a motion region;

a motion direction detection step which performs an exclusive of frame difference signal sign bits and sum signal sign bits of horizontal and vertical difference signals with respect to respective input signals and 1 frame-delayed signals in order to detect left/right motion direction and up/down motion direction; and a motion magnitude detection steps which detects a horizontal motion magnitude with regard to a K×3 window and a vertical motion magnitude with regard to a K×2 window by a ratio of frame difference signal absolute value sums and horizontal/vertical difference signal absolute value sums.

step A which generates vertical difference signals with respect to incoming signals and 1 frame-delayed signals of it respectively, adds the 2 vertical difference signals and generates absolute values of the added values;

step B which generates horizontal difference signals with respect to incoming signals and 1 frame-delayed signals of it respectively, adds the 2 horizontal difference signals and generates absolute values of the added values;

step C which obtains frame difference signals with respect to incoming image signals and converts then to absolute values; and

step D which compares outputs of the step C with certain critical values, compares outputs of the step C with those of the step A, compares output of the step B with those of the step A and ORs the compared outputs.

step D which performs an exclusive OR with respect to outputs of the step C and those of the step B in order to detect a left/right motion and performs an exclusive OR with respect to outputs of the step C and those of the step A in order to detect and up/down motion.

substep d4 which divides outputs of the substep d2 by outputs of substep d3 in order to detect horizontal motion magnitudes and divides outputs of the substep d1 by outputs of the substep d3 in order to detect vertical motion magnitudes.

a dividing element for estimating a vertical motion by a ratio of sums of multiplications of frame difference signals and vertical difference signal signs from the 3rd sample accumulating section and sums of vertical difference signal absolute values from the 1st sample accumulating section; and

a dividing element for estimaqting a horizontal motion by a ratio of sums of multiplications of frame difference signals and horizontal difference signal signs from the 4th sample accumulating section and sums of horizontal difference signal absolute values from the 2nd sample accumulating section.

substep e1 which generates its outputs after accumulating output signals of the step A by k samples;

substep e2 which generates its outputs after accumulating output signals of the step B by k samples;

substep e3 which generates its outputs after accumulating sums of mutiplications of frame difference signals and vertical difference signal signs of the substep e1 by k samples;

substep e4 which generates its outputs after accumulating sums of mutiplications of frame difference signals and horzontal difference signal signs of the substep e2 by k samples; and

substep e5 which estimates a vertical motion by a ratio of sums of multiplications of frame difference signals and vertical difference signal signs from the substep e3 and sums of vertical difference signal absolute values from the substep e1, and estimates a horizontal motion by a ration of sums of multiplications of frame difference signals and horizontal difference signal signs from the substep e4 and sums of vertical difference signal absolute values from the substep e2.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is related to image motion detection and image motion estimation, and more particularly to motion detection and estimation apparatus and method thereof for providing motion direction detection and motion estimation together with reduced motion detection error due to taking an image motion into account in both time and space axes.

2. Description of the Prior Art

Conventional motion detection apparatus as shown in FIG. 1, is constituted with an 1-frame memory means 1 which generates a signal delayed by 1-frame in regard to coming image signals Y, a subtracting element 2 which performs subtraction between the coming image signals Y and the signal delayed by 1-frame in the 1-frame memory means 1, a lowpass filtering elements 5 which filters signals generated from the subtracting element 2, an absolute value generating means 3 which converts frame difference signals of the subtracting element 2 into absolute values and n comparison means 4 which generates motion detection signals by comparing certain critical values TH1-THn with the absolute values from the absolute value generating means 3.

In the above-mentioned conventional motion detection apparatus, a motion detection method is one that a decision on an image motion is made in case that a magnitude of a difference signal between a present frame and a prior frame is higher than a certain critical value or in case that a magnitude of the difference signal filtered through a lowpass filtering element is higher than a certain critical value.

The subtracting element 2 calculates 1-frame difference signals from the image signals Y delayed by 1-frame which are generated from the 1-frame memory means 1. The 1-frame difference signals are converted to absolute values by the absolute value generating means 3.

If the absolute values of 1-frame difference signals are higher than certain critical values TH1, the 1st comparison means 4 generates a high logical value 1 with judging that motions of an image region exist. If the absolute values are lower than the certain critical values TH1, the 1st comparison means 4 generates a low logical value with judging that the image region remains still.

The lowpass filtering element 5 is used for error reduction of motion detection signals caused by noise signal. The 1st to Nth comparison means detect various motion magnitudes according to their critical values TH1-THn.

FIGS. 2A and 2B are schematic diagrams according to sampling lattice of NTSC signals of 480 active lines in a conventional image motion detection method.

FIGS. 3A and 3B show Nyquist regions of baseband signals, which are shaded portions A and B. If an image motion in both horizontal/vertical directions and times axes still exists in the Nyquist region, it is judged that the image motion is not occurred in such directions.

As shown in FIG. 4A, in case that a signal change in the time axis is larger than a certain level and aliasing C between spectrums occurs, it is judged that an image motion occurs.

However, in case that a large image motion in the vertical direction occurs with a signal change in the axis less than a certain level, it is judged that an image motion occurs by a frequency aliasing component D in the vertical direction as shown in FIG. 4B. This phenomenon is also applied to the horizontal direction.

The conventional image motion detection method which takes only an image motion in the time axis into account without any consideration of its motion in space does not detect motion directions. And also, the conventional method has a problem of a poor accuracy in detecting image motion magnitudes. That is, an image region with a small image motion magnitude in space is judged as that with a large image motion magnitude or vice versa.

SUMMARY OF THE INVENTION

The present invention is related to motion detection and estimation apparatus and method thereof for performing accurate motion detection or motion magnitude detection, motion direction judgement and motion magnitude estimation in order to solve the above-mentioned problems of the prior art.

The present invention can be used for signal processing such as scan line interpolation and field rate increase; enhancement when using a function of motion direction detection of the present invention; and luminance/chromaticity separation and video data compression, etc.

The present invention can perform more accurate motion detection than the prior art through its motion detection apparatus since horizontal and vertical image motion rates are taken into account, and detect motion direction of an article in an image motion region through a function of its motion direction detection, whereas a motion detection means of the prior art has not a function of motion direction detection.

The present invention also provides both functions of judgement on whether or not a motion exists and motion magnitude measurement.

The present invention also provides a simple method of motion estimation in a K×3 search region through its motion estimation means whose vertical and horizontal search regions can be respectively expanded by increasing K-sample memory and line memory in number.

The motion detection apparatus of the present invention is composed of a motion region detection means which compares frame difference signal absolute values with certain critical values, compares the frame difference signal absolute values with absolute values of horizontal/vertical signal sums with respect to incoming signals and 1-frame-delayed signals, judges as a stillness region if the frame difference signals are less with certain critical values in all the comparisons, and judges as a motion region if not;

a motion direction detection means which performs an exclusive OR of both the frame difference signal sign bits and horizontal/vertical difference signals, and detects a motion direction MD with respect to horizontal directions (left, right) and horizontal directions (up, down); and

a motion magnitude detection means which detects a horizontal motion magnitude MM by a ratio of frame difference signal absolute value sums and horizontal difference signal absolute value sums with respect to window of sample and line memory numbers, and detects a vertical motion magnitude MM by a ratio of frame difference signal absolute value sums.

A motion estimation for a horizontal motion dx and a vertical motion dy are accomplished as follows.

That is, absolute values of vertical/horizontal difference signal sums with respect to 3 lines and sums of vertical/horizontal difference signal absolute values in regard to a K×3 window are respectively generated by accumulating element and K-sample memory. Frame difference signals with respect to the 3 lines are multiplied by horizontal/vertical difference signal sign bits with respect to the 3 lines. And then, sums of multiplications of the frame difference signals and horizontal/vertical difference signal sign bits in regard to the K×3 window is generated by accumulating element and K-sample memory for horizontal/vertical motion estimations.

The present invention uses horizontal and vertical signals of an image as critical values for a motion detection judgement. The present invention detects horizontal motion direction (left, right) and vertical motion directions (up, down) by a result of exclusive OR of horizontal/vertical difference signals and frame difference signals. The present invention takes into account image motions (horizontal and vertical) in space by using a ratio of horizontal/vertical difference signal sums and frame difference signal sums with respect to the K×3 window.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows conventional motion detection apparatus;

FIGS. 2A and 2B show schematic diagrams of sampling lattice of NTSC signals;

FIGS. 3A and 3B are schematic diagrams of Nyquist regions shown in FIGS. 2A and 2B;

FIGS. 4A and 4B show schematic diagrams of spectrum aliasing phenomenon according to image motions;

FIG. 5 shows a schematic diagram of motion detection apparatus according to the present invention;

FIGS. 6A to 6E show waveforms illustrating motion direction detection when motions occur according to the present invention;

The present invention will be described below in detail through preferred embodiments with reference to attached drawings.

FIG. 5 shows a schematic diagram of motion detection apparatus according to the present invention.

As shown in FIG. 5, the motion detection apparatus according to the present invention is constituted with a motion region detection means 100 which compares frame difference signal absolute values with certain critical values, compares the frame difference signal absolute values with absolute values of horizontal/vertical signal sums with respect to incoming signals and 1 frame-delayed signals of the incoming signals, judges as a stillness region if the frame difference signals are less in all the comparisons, and judges as a motion region MR if not; a motion direction detection means 200 which performs an exclusive OR of the frame difference signal sign bits and horizontal difference signals or vertical difference signals, and detects a motion direction MD with respect to horizontal directions (left, right) and horizontal directions (up, down); and a motion magnitude detection means 300 which detects horizontal motion magnitudes MM by ratios of sums of frame difference signal absolute values and sums of horizontal difference signal absolute values with respect to window of sample and line memory numbers, and detects vertical motion magnitudes MM by ratios of sums of frame difference signal absolute values and sums of vertical difference signal absolute values.

The frame difference signal generating element 531 is constituted with a 1-frame memory element which delays incoming image signals by 1 frame; and a subtracting element which performs a subtraction with the incoming image signals Y.

The vertical difference signal generating element is constituted with a 1-line memory element which delays respectively incoming image signals by 1 line; and a subtracting element which generates differences between output image signals of the 1-line memory and incoming image signals Y.

The horizontal difference signal generating element is constituted with a 1-sample memory element which delays incoming image signals Y by 1 sample; and a subtracting element which generates differences between image signals of the 1-sample memory element and the incoming image signals Y.

The motion direction judging section 640 is constituted with an exclusive OR gate element EX-OR2 which performs an exclusive OR of outputs from the 1 frame difference signal generating section 630 and the interframe horizontal difference signal generating section 620 and judges whether or not motions in left and right directions exist; and an exclusive OR gate element EX-OR3 which performs an exclusive OR of outputs from the 1 frame difference signal generating section 630 and the interframe horizontal difference signal generating section 620 and judges whether or not motions in up and down directions exist.

FIG. 9 shows a logic diagram for a function of motion direction detection in motion apparatus according to the present invention.

The interframe vertical difference signal absolute value generating elements are respectively constituted with a 1 line memory element which delays 1 frame-delayed signals by 1 line; an adding element which adds incoming image signals delayed by 1 line and 1 frame image signals; and an absolute value generating element which generates outputs of the adding element to absolute values.

The sample accumulating elements are respectively constituted with a k sample memory element which delays incoming signals by k samples; a subtracting element r which generates differences between the incoming signals and the k sample-delayed signals; and an accumulating element which accumulates outputs of the subtracting element by k samples.

FIG. 11 shows a block diagram for motion estimation apparatus according to the present invention.

The complement generating section are respectively constituted with an inverting element which inverts horizontal difference signal signs; a 1st complement generating element which generates complements according to outputs of the inverting element and the frame difference signals; and a 2nd complement generating element which generates complements according to outputs of the inverting element, the frame difference signals and the inverting element which inverts the vertical difference signals signs.

Operations and effects of the present invention with the above-mentioned constitution will be described below in detail with reference to drawings from FIG. 5 to FIG. 12.

FIGS. 6A to 6E show motion direction detection when a motion occurs according to the present invention. In case that a motion occurs to the right as shown in FIG. 6A, frame difference signals FD, present frame FO - prior frame F-1 appear as shown in FIG. 6B, and pixel difference signals SDo, present pixel Xo - prior pixel X-1 in space region appear as shown in FIG. 6C.

According to the above-mentioned, sum signals TSDo of pixel difference signals SDo1 in prior frame and pixel difference signals SDo2 in present frame appear as shown in FIG. 6D, an output of exclusive OR of sum signals TDSo of pixel differences in the present and prior frames and frame difference signals FD appears as shown in FIG. 6E.

Therefore, it is indicated that a motion to the right occurs in case that the exclusive OR output of the pixel difference signals TDSo and frame difference signals FD in a motion region goes to a logic 1, while it is indicated that a motion to the left occurs in case that the exclusive OR output goes to a logic 0.

Such a motion detection method will be described below in detail with respect to FIG. 7.

Input signals are delayed by 1 line in 1 line memory element 101 and vertical direction difference signals are generated from a subtracting element 103. And also, image signals are delayed by 1 sample in 1 sample memory element 104 and horizontal direction difference signals are generated from a subtracting element 105. 1 frame-delayed signals are produced from 1 frame memory element 106 and 1 frame difference signals are out of a subtracting element 107.

And, horizontal difference signals with respect to input signals and horizontal difference signals with respect to 1 frame-delayed signals are added by an adding element 114, the added signals are converted to absolute values through an absolute value generating element 117. Vertical difference signals and 1 frame-delayed signals with respect to incoming signals are also added by an adding element 115 and added signals are converted to absolute values through absolute value generating element 118.

Absolute values to which frame difference signals of the subtracting element 107 are converted through an absolute value generating element 116 are compared with certain critical values and absolute values of horizontal and vertical difference signals sums in respective comparing elements 119-121. If at least one of the comparing elements 119-121 has logic 1 outputs, it is judged that motions exist. If not, it is judged that motion does not exist.

A value obtained from exclusive-OR gate element EX-OR2 of frame difference signal sign bits which are obtained from subtracting element 206 and sign bits of outputs of the adding element 212 is a detection signal which indicates a horizontal motion direction, i.e., left and fight motion directions LRMD. It is indicated that a motion occurs to the right if the value is a logic 1, and it is indicated that a motion occurs to the left if the value is a logic 0.

And also, a value obtained from exclusive-OR gate element EX-OR3 of frame difference signal sign bits and sign bits of outputs of the adding element 213 is a detection signal which indicates a vertical motion direction, i.e., up and down motion directions UDMD. It is indicated that a motion occurs to the down direction if the value is a logic 1, and it is indicated that a motion occurs to the up direction if the value is a logic 0.

FIG. 9 shows a logic diagram for a function of motion direction detection in motion detection apparatus according to the present invention. This FIG. 9 also shows a motion detection method that FIG. 7 and FIG. 8 are integrated. A result that a motion region MR detection signal and a left/right motion direction LRMD detection signal are ANDed through AND gate AND 1 indicates information HG on a horizontal motion, and a result that a motion region MR detection signal and a up/down motion direction UDMD detection signal are ANDed through AND gate AND2 indicates information VG on a vertical motion.

As shown in FIG. 10, vertical and horizontal difference signals are generated through a 1 line memory element 301 and a subtracting element 302 and through a 1 sample memory 304 and a subtractor 305, and the vertical and horizontal difference signals are converted to absolute values through absolute value generating elements 303, 306. 1 line-delayed signals are generated through a 1 line memory element 310 and a subtracting element 311 and through a 1 sample memory element 313 and a subtracting element 314, and the vertical and horizontal difference signals are converted to absolute values through absolute value generating element 312, 315. 2 line-delayed signals are converted to horizontal difference signals through a 1 sample memory element 316 and a subtracting element 317, and the horizontal difference signals are converted to absolute values through absolute value generating element 318. And also, 1 frame-delayed signals from a 1 frame memory element 307 are combined with 1 line-delayed signals through a 1 line memory element 321 and a subtracting element 322, and the combined signals are converted to absolute values through an absolute value generating 323. 1 frame/2 line-delayed signals through a 1 line memory element 325 and a subtracting element 326 with which 2 line-delayed signals are combined are converted to absolute values through an absolute value generating element 327. Input signals are generated as frame difference signals through a 1 frame memory element 307 and a subtracting element 308 which are converted to absolute values through an absolute value generating element 309.

Here, a value over 5 or 7 are to be chosen for the K value in case of T.V. image signals since horizontal motion magnitudes are larger than vertical ones. And expanded vertical detection region can be accomplished with increased sample memory number in k sample memory elements 330, 333, 336.

Here, dx and dy are respectively expressed when linear regression and cross term of x,y are ignored. ##EQU4##

The present invention with such motion detection, motion direction detection and motion estimation can be used for a signal processing such as scan line interpolation and field rate increase; and enhancement by using a function of motion direction detection of the present invention.

And also, the present invention with motion detection, motion direction detection and motion estimation can be used for separation of luminance and chromaticity, video data compression and so on.

As above mentioned in detail, conventional motion detection apparatus which uses only frame difference signals are under the influence of horizontal and vertical change rates of an image. The motion detection apparatus of the present invention can perform more accurate motion detection than prior art since horizontal and vertical image motion rates are taken into account. The present invention detects article motion direction through a function of its motion direction detection, whereas a motion detection apparatus of prior art has not a function of motion direction detection.

The present invention also provides measurement of a motion magnitude, whereas conventional motion detection apparatus just judges whether or not a motion exists.

And the motion estimation apparatus of the present invention provides a simple method which motion estimation can be done in a K×3 search region. There exists effects in that expanded search region in the horizontal direction can be obtained with increased k sample memory element number and expanded search region in the vertical direction can be obtained with increased line memory elements number.